1. Field of the Invention
This invention relates to a system for controlling the operation of a numerically controlled machine tool used for cutting threads on workpieces, in which means are provided so that the quality of the products may not be adversely affected even when the thread cutting operation may be interrupted for some reasons incidental to the thread cutting.
2. Description of the Prior Art
A numerically controlled machine tool is employed widely for cutting threads on workpieces. While the numerically controlled machine tool can satisfactorily work for this purpose, a trouble tending to give rise to breakage of the threading tool or tending to produce a reject has frequently occurred when the chips twine around the workpiece being machined. Although the chips can be manually removed after interrupting the motion of the tool slide, mere interruption on the motion of the tool slide only for the removal of the chips has inevitably resulted in such an objectionable situation that a groove of substantial width is necessarily formed which renders the product unfit for use as a mechanical part.